Blind transport format detection for communication

ABSTRACT

A receiver ( 300 ) is provided that efficiently determines what transport format combination is currently being utilized by a transmitter ( 200 ) multiplexing ( 201 ) several transport channels onto a single over-the-air channel ( 209 ). The receiver ( 300 ) estimates the transmitted sequence and, not knowing the format combination being utilized, makes estimates of the information bits for each of the possible transport format combinations. CRC metrics are determined (one for each transport or data channel) for each possible transport format combination, and these CRC metrics are combined into a single transport format combination metric for the particular transport format combination being tested.

FIELD OF THE INVENTION

[0001] The present invention relates generally to communication systemsand in particular, to blind transport format detection within suchcommunication systems.

BACKGROUND OF THE INVENTION

[0002] During communication, a mobile unit may be transmitting severaldiffering data streams (transport channels) over a single over-the-airchannel. For example, control and application data may be multiplexedonto a single over-the-air channel transmitted to infrastructureequipment. Each data stream may be capable of being transmitted inseveral formats. For example, each data stream has its own bit rate,channel coding type, block size, transmission time interval (TTI). . . ., etc.

[0003]FIG. 1 illustrates the multiplexing of two data streams. Althougheach data stream may in actuality be capable of transmitting in manydiffering transport formats (TFs), for simplicity data streams 101 and102 are shown having only two transport formats. As shown data stream 1is capable of transmitting at 0 or 9.6 Kbps, while data stream 2 iscapable of transmitting at 0 or 300 Kbps. That is, data stream 1 has twodiffering TFs, with TF₁₁=0 Kbps and TF₁₂=9.6 Kbps, while data stream 2also has two differing transport formats with TF₁₂=0 Kbps and TF₂₂=300Kbps.

[0004] At any given time, each data stream may be transmitting any oftheir various transport formats. For example, a transport formatcombination (TFC) of TF₁₁=0 Kbps, and TF₂₂=300 Kbps may be enteringmultiplexer 101. As illustrated in FIG. 1, there exists four transportformat combinations, with TFC1={TF₁₁, TF₂₁}, TFC2={TF₁₁, TF₂₂},TFC3={TF₁₂, TF₂₁}, and TFC4={TF₁₂, TF₂₂}. In general, if there exists Itransport channels each of which has J_(i) transport formats, thereexists $\prod\limits_{i = 1}^{I}J_{i}$

[0005] possible transport format combinations.

[0006] During blind transport format detection, a receiver has noindication which of the $K = {\prod\limits_{i = 1}^{I}J_{i}}$

[0007] possible transport format combinations is being utilized by thetransmitter. Prior-art solutions to the problem have dealt withdetermining the transport format of a single channel only. For example,section A.1.2 of the 3^(rd) Generation Partnership Project (3GPPP) TS25.212 v3.5.0 describes a blind transport format detection of a singledata channel using a cyclic-redundancy check (CRC). Such prior-artmethods fail to describe the determination of a transport format wheremultiple data channels are multiplexed onto a single over-the-airchannel. Therefore, a need exists for a blind transport format detectionfor a received signal that efficiently determines what transport formatcombination is currently being utilized by a transmitter multiplexingseveral transport channels onto a single over-the-air channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008]FIG. 1 illustrates prior-art data transmission.

[0009]FIG. 2 is a block diagram of a transmitter in accordance with thepreferred embodiment of the present invention.

[0010]FIG. 3 is a block diagram of a receiver in accordance with thepreferred embodiment of the present invention.

[0011]FIG. 4 is a flow chart showing operation of the receiver inaccordance with the preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0012] To address the above-mentioned need, a receiver is provided thatefficiently determines what transport format combination is currentlybeing utilized by a transmitter multiplexing several transport channelsonto a single over-the-air channel. The receiver described belowestimates the transmitted sequence and, not knowing the transport formatcombination being utilized, makes estimates of the information bits foreach of the possible transport format combinations. Cyclic RedundancyCheck (CRC) metrics are determined (one for each transport or datachannel) for each possible transport format combination, and these CRCmetrics are combined into a single transport format combination metricfor the particular transport format combination being tested.

[0013] Testing all possible transport format combinations results inmultiple CRC metrics for each transport format combination, and a singletransport format combination metric for each possible transport formatcombination. The transport format combination with the greatesttransport format combination metric is the estimate of the transportformat combination that is currently being utilized by the transmitter.

[0014] The present invention encompasses a method for blind transportformat detection. The method comprising the steps of receiving anover-the-air signal comprising a plurality of transport channelsmultiplexed onto the over-the-air signal, wherein each of the pluralityof transport channels comprises a plurality of transport formats, anddetermining a plurality of Cyclic Redundancy Check (CRC) metrics foreach of the transport channels and a first transport format. Inaddition, a transport format combination metric is determined based onthe plurality of CRC metrics and a transport format is determined basedon the transport format combination metric.

[0015] The present invention additionally encompasses a method for blindtransport format detection. The method comprises the steps of (a)receiving an over-the air signal comprising I data (transport) channels,(b) determining I Cyclic Redundancy Check (CRC) metrics for the I datachannels, and (c) determining a transport format combination metric forthe I data channels based on the CRC metrics for the I data channels.Steps b-c are repeated for each possible transport format combination,and a transport format combination is determined corresponding to alargest transport format combination metric.

[0016] The present invention additionally encompasses an apparatuscomprising a de-multiplexer having a data stream as an input, whereinthe data stream comprises a plurality of transport channels, each havinga plurality of transport channel formats, the de-multiplexer outputtinga plurality of channels based on a particular transport formatcombination, a plurality of Cyclic Redundancy Checking (CRC) circuitry,each having one of the plurality of channels as an input and outputtinga CRC for the channel, and a logic unit having a plurality of CRC valuesas an input and outputting a transport format combination metric basedon the plurality of CRC values.

[0017] Turning now to the drawings, wherein like numerals designate likecomponents, FIG. 2 is a block diagram of transmitter 200 in accordancewith the preferred embodiment of the present invention. As shown,transmitter 200 comprises, rate matcher 203, multiplexer 201, andspreader 205. As shown, I transport channels enters rate matcher 203,where information bits from each transport channel are punctured orrepeated. The I outputs of the rate matcher 203 are multiplexed onto asingle data stream identified as a Coded Composite TransportChannelchannel (CCTrCH). Spreader 205 spreads the data stream with achannelization code whose length is variable depending on the data rateof the CCTrCH and outputs a channel stream having a constant chip rate.In particular, since data entering spreader 205 may have one of manydiffering data rates, spreading circuitry 205 appropriately spreads thedata with one of several available channelization codes in order toachieve a constant output chip rate. The channel stream is thenmodulated and transmitted via antenna 207.

[0018] In the preferred embodiment of the present invention transmitter200 multiplexes several data channels (transport channels) onto a singleover-the-air channel 209. Each transport channel has a plurality oftransport formats suitable for transmission. As discussed above, for theI transport channels (each of which has J_(i) transport formats), thereexists K possible transport format combinations (TFCs), where$K = {\prod\limits_{i = 1}^{I}{J_{i}.}}$

[0019] While there exists methods for a receiver to determine atransport format when a single data channel (transport channel) isutilized, there currently exists no method to determine a transportformat combination where several transport channels are multiplexed ontoa single binary sequence. In order to solve this problem, the receiverof FIG. 3 is provided.

[0020]FIG. 3 is a block diagram of receiver 300 in accordance with thepreferred embodiment of the present invention. As shown receiver 300comprises despreader 301, rate matcher 307, de-multiplexer 305, decoder309, CRC check 311, and logic unit 313. In the preferred embodiment ofthe present invention receiver 300 estimates the transmitted sequenceand, not knowing the format combination being utilized, makes estimatesof the information bits for each of the $\prod\limits_{i = 1}^{I}J_{i}$

[0021] possible transport format combinations. I CRC metrics aredetermined (one for each transport or data channel) for each possibletransport format combination, and these I CRC metrics are combined intoa single transport format combination metric for the particulartransport format combination being tested. Testing all$\prod\limits_{i = 1}^{I}J_{i}$

[0022] possible transport format combinations results in I CRC metricsfor each transport format combination, and a single transport formatcombination metric for each possible transport format combination. Thetransport format combination with the greatest transport formatcombination metric is the estimate of the transport format combinationthat is currently being utilized by transmitter 200.

[0023] Operation of receiver 300 occurs as follows: Logic unit 313 knowsthe possible transport formats via Layer-3 negotiation as described inTS section 8.2.5 of the 3^(rd) Generation Partnership Project (3GPPP) TS25.331 v3.2.0. Over-the-air signal 209 enters de-spreader 301 and isdespread according to the shortest channelization code used in the setof possible transport format combinations and stored in buffer 302. Thedespread signal is passed to a linear combiner 303 where appropriatecombining to form a channel symbol for a first transport formatcombination (TFC_(n)) is accomplished. The linear combinations utilizedby linear combiner 303 are based on the current transport formatcombination being utilized by the receiver. For example, suppose thereare two transport format combinations. The data rate of the multiplexedtransport channels under the first transport format combination requiresa spreading factor of 32, i.e., each channel symbol is spread by a 32chip sequence. With the second transport format combination, themultiplexed transport channels has a smaller data rate and only requiresa spreading factor 64. The channelization code of length 64 is equal tothe concatenation of the 32 chip channelization code used under thefirst transport format combination. Despreading with the 64 chip codecan therefore be accomplished by first dispreading consecutive 32 chipsegments of the received signal, storing the two results in a buffer,and summing, that is linearly combining them. (See TS section 4.3.1 ofthe 3^(rd) Generation Partnership Project (3GPPP) TS 25.213 v3.2.0.) Thecombining coefficient utilized by linear combiner 303 are based uponcurrent transport format combination being utilized, and are input fromlogic circuitry 313.

[0024] The resulting binary sequence are routed to de-multiplexer 305.In particular, de-multiplexer 305 de-multiplexes the data streamaccording to a particular transport format combination (in this exampleTFC_(n)). This results in I data streams, one for each transportchannel. This is followed by rate de-matching circuitry 305 that servesto insert dummy information bits where bits were punctured in the ratematcher 203 (FIG. 2) or combine bits where bits were repeated in therate matcher 203 (FIG. 2).

[0025] The I data streams are each decoded and passed to CRC checkcircuitry 305, where an appropriate CRC metric is obtained for eachchannel. The data stream is also stored in storage 315. The CRC metricsare then passed to logic circuitry 313 where an appropriate transportformat combination metric is determined for TFC_(n). The above processcontinues (in serial or parallel) until a transport format combinationmetric is determined for all possible transport format combinations.Once a transport format combination metric has been determined for alltransport format combinations, logic unit 313 instructs storage 315 topass the decoded data associated with the largest transport formatcombination metric.

[0026] Determination of Transport Format Combination Metric

[0027] As described above, transmitter 200 encodes, rates matches andcombines the plurality of transport channels into a single binarysequence. The sequence is modulated and transmitted. Receiver 300estimates this sequence and, not knowing the format combination inforce, makes estimates of the information bits under each possibleformat combination hypothesis. The estimate of ith transport channeldata vector under the hypothesis of format combination k is denotedû_(i)^(k).

[0028] Therefore, for each hypothesized format combination, k, k=1,2, .. . K, a set of estimated vectors$\left\{ {{\hat{\underset{\_}{u}}}_{i}^{k},{i = 1},2,\quad \ldots \quad,I} \right\}$

[0029] are generated. Let c_(i)^(k)

[0030] be equal to ‘1’ if the ith transport channel data estimate,û_(i)^(k),

[0031] under the format combination hypothesis k, is correct, i.e., isequal to the true ith transport channel data u_(i): $\begin{matrix}{c_{i}^{k} = \left\{ {\begin{matrix}{1,} & {{\hat{\underset{\_}{u}}}_{i}^{k} = {\underset{\_}{u}}_{i}} \\{0,} & {{\hat{\underset{\_}{u}}}_{i}^{k} \neq {\underset{\_}{u}}_{i}}\end{matrix},{i = 1},2,\ldots \quad,{{I\quad {and}\quad k} = 1},2,\quad \ldots \quad,K} \right.} & (1)\end{matrix}$

[0032] In other words, c_(i) ^(k) is equal to ‘1’ when the decoded datafor the ith transport channel is correct.

[0033] Define c ^(k) to be the vector $\begin{matrix}{{{\underset{\_}{c}}^{k} = \left\lbrack {c_{1}^{k}c_{2}^{k}\quad \ldots \quad c_{I}^{k}} \right\rbrack},{k = 1},2,\ldots \quad,K} & (2)\end{matrix}$

[0034] and the collection of these vectors into the matrix C

C=[c ¹ c ² . . . c ^(K)]^(T).  (3)

[0035] Obviously, given k=k, matrix C has the following form:$C = {\begin{bmatrix}\underset{\_}{0} \\\vdots \\\underset{\_}{0} \\{\underset{\_}{c}}^{k} \\\underset{\_}{0} \\\vdots \\\underset{\_}{0}\end{bmatrix}\begin{bmatrix}0 & 0 & \cdots & 0 \\\vdots & \quad & \quad & \vdots \\0 & 0 & \quad & 0 \\c_{1}^{k} & c_{2}^{k} & \cdots & c_{I}^{k} \\0 & 0 & \quad & 0 \\\vdots & \quad & \quad & \vdots \\0 & 0 & \cdots & 0\end{bmatrix}}$

[0036] where $\begin{matrix}{{{P\left( {c_{i}^{k} = 0} \right)} = {{P\left( {{{{\hat{\underset{\_}{u}}}_{i}^{k} \neq u_{i}}k} = k} \right)} = e_{i}^{k}}},{i = 1},2,\quad \ldots \quad,{I\quad {and}}} & (4) \\{{{P\left( {c_{i}^{k} = 1} \right)} = {{P\left( {{\hat{\underset{\_}{u}}}_{i}^{k} = {\left. u_{i} \middle| k \right. = k}} \right)} = {1 - e_{i}^{k}}}},{i = 1},2,\quad \ldots \quad,{I.}} & (5)\end{matrix}$

[0037] A CRC check is performed on each of the estimated transportchannel data vectors$\left\{ {{\hat{\underset{\_}{u}}}_{i}^{k},{i = 1},2,\ldots,I} \right\}$

[0038] for each transport combination hypothesis to yield a set ofbinary valued variables, {r_(i)^(k), i = 1, 2, …  , I},

[0039] where k=1,2, . . . K, r_(i)^(k)

[0040] is equal to ‘1’ if the p_(i) bit CRC of the ith transport channelpasses on the vector on vector u ₁ ^(k) and ‘0’ otherwise.

[0041] The CRC checks corresponding to format combination k areorganized into the vector $\begin{matrix}{{{\underset{\_}{r}}^{k} = \left\lbrack {r_{1}^{k}r_{2}^{k}\quad \ldots \quad r_{I}^{k}} \right\rbrack},{k = 1},2,\ldots \quad,K} & (6)\end{matrix}$

[0042] and the combination of these vectors into the observation matrixR:

R=[r ¹ r ² . . . r ^(K)]^(T).  (7)

[0043] The problem is to estimate kε{1,2, . . . ,K}, the transportformat combination, given the set of CRC checks R. The solution wouldthen be $\begin{matrix}{\hat{k} = {\underset{k \in {\{{1,2,\quad \ldots \quad,K}\}}}{argmax}{\left\{ {P\left( {R,C,k} \right)} \right\}.}}} & (8)\end{matrix}$

[0044] Decomposition of P(R,C,k):

[0045] Taking the log of P(R,C,k) gives $\begin{matrix}\begin{matrix}{{\ln \quad {P\left( {R,C,k} \right)}} = \quad {{\ln \quad {P\left( {{RC},k} \right)}} + {\ln \quad {P\left( C \middle| k \right)}} + {\ln \quad {P(k)}}}} \\{= \quad {{\ln \quad {P\left( {{R{\underset{\_}{c}}^{k}},k} \right)}} + {\ln \quad {P\left( {\underset{\_}{c}}^{k} \middle| k \right)}} + {\ln \quad {P(k)}}}}\end{matrix} & (9)\end{matrix}$

[0046] The first term can be simplified by making the reasonableassumption that r ¹, r ², . . . r ^(K) are conditionally independentgiven c ^(k) and k. We then have $\begin{matrix}\begin{matrix}{{\ln \quad {P\left( {R,C,k} \right)}} = \quad {{\sum\limits_{\underset{j \neq k}{j = 1}}^{K}{\ln \quad {P\left( {\left. {\underset{\_}{r}}^{j} \middle| {\underset{\_}{c}}^{k} \right.,k} \right)}}} + {\ln \quad {P\left( {{{\underset{\_}{r}}^{k}{\underset{\_}{c}}^{k}},k} \right)}} +}} \\{\quad {{\ln \quad {P\left( {\underset{\_}{c}}^{k} \middle| k \right)}} + {\ln \quad {{P(k)}.}}}}\end{matrix} & (10)\end{matrix}$

[0047] The first two terms are two statistics based on received data.The remaining terms are a priori information.${{Calculation}\quad {of}\quad {\underset{j \neq k}{\sum\limits_{j = 1}^{K}}{\ln \quad {P\left( {{{\underset{\_}{r}}^{j}{\underset{\_}{c}}^{k}},k} \right)}}}}:$

[0048] The CRC results for the transport channel data estimate vectorsunder the transport format combination hypothesis different from the onein force are independent of the correctness of the transport channeldata estimate under the hypothesis of the transport combination inforce, i.e.,

P( r ^(J) |c ^(k) ,k)=P( r ^(J) |k), j≠k.  (11)

[0049] The CRC results for different transport channels are alsoindependent $\begin{matrix}{{{\ln \quad {P\left( {{\underset{\_}{r}}^{j}k} \right)}} = {\sum\limits_{i = 1}^{I}{\ln \quad P\text{(}r_{i}^{j}\text{}k\text{)}}}},{j \neq {k.}}} & (12)\end{matrix}$

[0050] The individual term in above is the log of the probability of theCRC passing for a wrong transport format combination. A commonapproximation to this probability is given by $\begin{matrix}{{{P\text{(}r_{i}^{j}}{k\text{)}}} = \left\{ {\begin{matrix}{\quad {2^{p_{i}},}} & {r_{i}^{j} = 1} \\{\quad {{1 - 2^{- p_{i}}},}} & {r_{i}^{j} = 0}\end{matrix}{or}} \right.} & (13) \\{{{\ln \quad P\text{(}r_{i}^{j}}{k\text{)}}} = \left\{ \begin{matrix}{{- p_{i}},} & {r_{i}^{j} = 1} \\{{{\ln \left( {1 - 2^{- p_{i}}} \right)} \approx 0},} & {r_{i}^{j} = 0.}\end{matrix} \right.} & (14)\end{matrix}$

[0051] We therefore have $\begin{matrix}{{\underset{j \neq k}{\sum\limits_{j = 1}^{K}}{\ln \quad {P\left( {{{\underset{\_}{r}}^{j}{\underset{\_}{c}}^{k}},k} \right)}}} = {{\underset{j \neq k}{\sum\limits_{j = 1}^{K}}{\sum\limits_{i = 1}^{I}{\ln \quad P\text{(}r_{i}^{j}\text{}k\text{)}}}} = {- {\underset{j \neq k}{\sum\limits_{j = 1}^{K}}{\sum\limits_{i = 1}^{I}{p_{i}{r_{i}^{j}.}}}}}}} & (15)\end{matrix}$

[0052] Calculation of 1nP(r ^(k)|c ^(k),k):

[0053] Under AWGN channel, the CRC results of the transport channels areindependent $\begin{matrix}{{\ln \quad {P\left( {{{\underset{\_}{r}}^{k}{\underset{\_}{c}}^{k}},k} \right)}} = {\sum\limits_{i = 1}^{I}{\ln \quad {{P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}.}}}} & (16)\end{matrix}$

[0054] The terms in the above can be evaluated from the following:$\begin{matrix}{{P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)} = \left\{ {\begin{matrix}{\quad {1,}} & {{c_{i}^{k} = 1},{r_{i}^{k} = 1}} \\{0,} & {{c_{i}^{k} = 1},{r_{i}^{k} = 0}} \\{2^{- p_{i}},} & {{c_{i}^{k} = 0},{r_{i}^{k} = 1}} \\{\quad {{1 - 2^{- p}},}} & {{c_{i}^{k} = 0},{r_{i}^{k} = 0}}\end{matrix}{or}} \right.} & (17) \\{{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}} = \left\{ \begin{matrix}{\quad {0,}} & {{c_{i}^{k} = 1},{r_{i}^{k} = 1}} \\{{- \infty},} & {{c_{i}^{k} = 1},{r_{i}^{k} = 0}} \\{{- p_{i}},} & {{c_{i}^{k} = 0},{r_{i}^{k} = 1}} \\{\quad {0,}} & {{c_{i}^{k} = 0},{r_{i}^{k} = 0}}\end{matrix} \right.} & (18)\end{matrix}$

[0055] Calculation of 1nP(c ^(k)|k):

[0056] Calculation of 1nP(c ^(k)|k) requires the joint transport channeldata block error rates. If these errors are independent, which is thecase for AWGN channel, we have $\begin{matrix}{{\ln \quad {P\left( {{\underset{\_}{c}}^{k}k} \right)}} = {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}} = \left\{ {\begin{matrix}{{\sum\limits_{i = 1}^{I}{\ln \quad e_{i}^{k}}},} & {c_{i}^{k} = 0} \\{{\sum\limits_{i = 1}^{I}{\ln \quad \left( {1 - e_{i}^{k}} \right)}},} & {c_{i}^{k} = 1}\end{matrix}.} \right.}} & (19)\end{matrix}$

[0057] Calculation of 1nP(k):

[0058] Assume the transmission of each transport format is equallylikely. We then have

1nP(k)=−1nK  (20)

[0059] which is a constant.

[0060] MAP Detection:

[0061] The MAP rule discussed before can be rewritten as $\begin{matrix}\begin{matrix}{\hat{k} = \quad {\underset{k}{\arg \quad \max}\left\{ {{- {\underset{j \neq k}{\sum\limits_{j = 1}^{K}}{\sum\limits_{i = 1}^{I}{p_{i}r_{i}^{j}}}}} + {\max\limits_{{\underset{\_}{c}}^{k}}\left\{ {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} +} \right.}} \right.}} \\\left. \left. \quad {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}} \right\} \right\} \\{= \quad {\underset{k}{\arg \quad \max}\left\{ {{\sum\limits_{i = 1}^{I}{p_{i}r_{i}^{k}}} + {\max\limits_{{\underset{\_}{c}}^{k}}\left\{ {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} +} \right.}} \right.}} \\{\left. \left. \quad {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}} \right\} \right\}.}\end{matrix} & (21)\end{matrix}$

[0062] For a given r ^(k), the c ^(k) which maximizes $\begin{matrix}{{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} + {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}}} & (22)\end{matrix}$

[0063] can be found from the following two observations:

[0064] 1) If  r_(i)^(k) = 0,

[0065] then the first term in (22) is −∞ unless c_(i)^(k) = 0.

[0066] Therefore $\begin{matrix}{{{\max\limits_{{\underset{\_}{c}}^{k}}\left\{ {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} + {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}}} \right\}} = {\sum\limits_{i = 1}^{I}{\ln \quad e_{i}^{k}}}},{c_{i}^{k} = {r_{i}^{k} = 0.}}} & (23)\end{matrix}$

[0067] 2) If r_(i) ^(k)=1, then $\begin{matrix}{{{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} + {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}}} = \left\{ \begin{matrix}{{{- p_{i}} + {\sum\limits_{i = 1}^{I}{\ln \quad e_{i}^{k}}}},{c_{i}^{k} = 0}} \\{{\sum\limits_{i = 1}^{I}{\ln \quad \left( {1 - e_{i}^{k}} \right)}},{c_{i}^{k} = 1}}\end{matrix} \right.} & (24)\end{matrix}$

[0068] Assuming e_(i)<0.5, i=1,2, . . . , I,k=1,2, . . . ,K, we have$\begin{matrix}{{{\max\limits_{{\underset{\_}{c}}^{k}}\left\{ {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} + {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}}} \right\}} = {\sum\limits_{i = 1}^{I}{\ln \quad \left( {1 - e_{i}^{k}} \right)}}},{c_{i}^{k} = {r_{i}^{k} = 1.}}} & (25)\end{matrix}$

[0069] Combining (23) and (25), we know that the maximizing c ^(k) isequal to r ^(k), i.e., $\begin{matrix}\begin{matrix}{{\max\limits_{{\underset{\_}{c}}^{k}}\left\{ {{\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {{r_{i}^{k}c_{i}^{k}},k} \right)}}} + {\sum\limits_{i = 1}^{I}{\ln \quad {P\left( {c_{i}^{k}k} \right)}}}} \right\}} = \quad {{\sum\limits_{i = 1}^{I}{\ln \quad e_{i}^{k}}} + {r_{i}^{k}\left( {{\ln \left( {1 - e_{i}^{k}} \right)} - {\ln \quad e_{i}^{k}}} \right)}}} \\{= \quad {{\sum\limits_{i = 1}^{I}{\ln \quad e_{i}^{k}}} + {r_{i}^{k}\ln \quad {\frac{1 - e_{i}^{k}}{e_{i}^{k}}.}}}}\end{matrix} & (26)\end{matrix}$

[0070] Substituting (26) into (21) gives $\begin{matrix}\begin{matrix}{\hat{k} = \quad {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}\left\{ {\sum\limits_{i = 1}^{I}\left( {{p_{i}r_{i}^{k}} + {r_{i}^{k}\ln \quad \frac{1 - e_{i}^{k}}{e_{i}^{k}}} + {\ln \quad e_{i}^{k}}} \right)} \right\}}} \\{\left. {= \quad {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}\left\{ {{\underset{i = 1}{\overset{I}{\sum(}}{\left( {p_{i} + {\ln \quad \frac{1 - e_{i}^{k}}{e_{i}^{k}}}} \right)r_{i}^{k}}} + {\ln \quad e_{i}^{k}}} \right)}} \right\}.}\end{matrix} & (27)\end{matrix}$

[0071]FIG. 4 is a flow chart showing operation of receiver 300 inaccordance with the preferred embodiment of the present invention. Thefollowing flow chart describes the procedure for determining a transportformat from the K hypothesized transport format combinations using theresults derived above.

[0072] The logic flow begins at step 401 where an over-the-air signal isreceived and properly despread by despreader 301 according to theshortest channel symbol (i.e., the channel symbol spread by the shortestchannelization code) in the transport format combination set. Theresulting shortest symbol stream exits despreader 301. It should benoted that different transport format combinations require furtherdespreading (linear combiner 303) with different channelization codes.In particular, since spreading was performed by the transmitter byspreading with differing-length channelization codes, despreading needsto take place utilizing these differing-length codes. Since eachtransport format combination requires further despreading with differingchannelization codes by linearly combining the shortest symbols, theshortest symbol stream exiting despreader 301 needs to be buffered atthe shortest symbol level for at least a whole radio frame (step 403).

[0073] To avoid buffering the signal at the chip level, in the preferredembodiment of the present invention the channelization codes used fordifferent transport format combinations of the transport formatcombination set all belong to the same code family. (See TS section4.3.1.1 of the 3^(rd) Generation Partnership Project (3GPPP) TS 25.213v3.2.0). Therefore, only the channel symbols with the shortestchannelization code (i.e., the parent code) need to be buffered at step403. Since the shortest code is the parent code of all other codes, thechannel symbols for different length of channel codes can be obtained bylinear combination of the shortest channel symbols.

[0074] As discussed above, a transport format combination metric willneed to be obtained for each transport format combination. Because ofthis, at step 405 k is set to 1 and logic unit 313 instructs despreader307 to despread the buffered signal using a channelization codeassociated with the kth transport format (step 407). In particular, atstep 407 the physical channel symbols are despread based on the shortestchannelization codes C_(ch,SF,i) used in the transport formatcombination set, where $i^{\prime} = \min\limits_{i}$

[0075] {i=SF_(k)/4,k=1,2, . . . K}, SF_(k) is the spreading factor forthe kth transport format combination. The physical channel symbols aredemodulated under transport format combination hypothesis TFC^(k) usingthe linear combination of the demodulated shortest channel symbols. TheI transport channel frames for the kth transport format combination isdecoded (step 409) and I CRC values obtained (step 411). In particular,for the kth transport format combination a CRC is obtained for each ofthe I channels. So for transport combination k, I CRC values areobtained (one for each data channel) to produce the decodinginformation: {CRC_(i)^(k), i = 1, 2, …  , I}.

[0076] These values and the decoded data are stored in storage 315 (step413) and the logic flow continues to step 415 where it is determined ifk=K, and if not k is incremented (step 417) and the logic flow returnsto step 407, otherwise the logic flow continues to step 419 wheretransport format combination metrics are determined for each of thetransport format combinations. In particular, when block error ratese_(i)^(k),

[0077] i=1,2, . . . ,I,k=1,2, . . . ,K are not available, the simplifiedform of (27) is used to determine the transport format combination:$\hat{k} = {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}\left\{ {\sum\limits_{i = 1}^{I}{p_{i}{CRC}_{i}^{k}}} \right\}}$

[0078] where p₁ε{24,16,12,8,0} and TF_(i)^(k)

[0079] equals to 1 if the TTI frame under hypothesis CRC_(i)^(k)

[0080] for the ith transport channel passes the CRC check; andCRC_(i)^(k)

[0081] equals to 0 if the TTI frame under hypothesis TF_(i)^(k)

[0082] fails the CRC check or CRC result is not available, e.g., in themiddle of the TTI boundary which happens when the transport format fordifferent transport channels have different TTI lengths.

[0083] Whenever the block error rates are made available throughmeasurement, (27) can be used for better accuracy:$\hat{k} = {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}{\left\{ {\sum\limits_{i = 1}^{I}\left( {{\left( {p_{i} + {\ln 1} - \frac{e_{i}^{k}}{e_{i}^{k}}} \right){CRC}_{i}^{k}} + {\ln \quad e_{i}^{k}}} \right)} \right\}.}}$

[0084] The estimated transport format for the ith transport channel isthen TF_(i)^(k̂)

[0085] It should be noted that if all CRCs are zero, the entire frameshall be declared as erasure. The transport format is assumed to be thesame as previous transport format.

[0086] Finally, at step 421, logic unit 313 instructs storage 315 topass decoded data associated with the largest transport formatcombination metric.

[0087] While the invention has been particularly shown and describedwith reference to a particular embodiment, it will be understood bythose skilled in the art that various changes in form and details may bemade therein without departing from the spirit and scope of theinvention. It is intended that such changes come within the scope of thefollowing claims.

1. A method for blind transport format detection, the method comprisingthe steps of: receiving an over-the-air signal comprising a plurality oftransport channels multiplexed onto the over-the-air signal, whereineach of the plurality of transport channels comprises a plurality oftransport formats; determining a plurality of Cyclic Redundancy Check(CRC) metrics for each of the transport channels and a first transportformat; determining a transport format combination metric based on theplurality of CRC metrics; and determining a transport format based onthe transport format combination metric.
 2. The method of claim 1wherein the step of receiving the over-the-air signal comprising theplurality of transport channels multiplexed onto the over-the-airsignal, wherein each of the plurality of transport channels comprisesthe plurality of transport formats comprises the step of receiving theover-the-air signal comprising the plurality of transport channelsmultiplexed onto the over-the-air signal, wherein each of the pluralityof transport channels comprises the plurality of transport formats,wherein the plurality of transport formats has a particular bit rate. 3.The method of claim 1 wherein the step of determining the transportformat combination metric based on the plurality of CRC metricscomprises the step of determining${\hat{k} = {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}\left\{ {\sum\limits_{i = 1}^{I}{p_{i}{CRC}_{i}^{k}}} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i) ^(k) for an ithtransport channel passes a CRC check; and CRC_(i) ^(k) equals to 0 ifthe TTI frame under hypothesis TF_(i)^(k)

fails the CRC check or a CRC result is not available.
 4. The method ofclaim 1 wherein the step of determining the transport format combinationmetric based on the plurality of CRC metrics comprises the step ofdetermining${\hat{k} = {\underset{k \in {\{{1,2,\ldots,K}\}}}{\arg \quad \max}\left\{ {\sum\limits_{i = 1}^{I}\left( {{\left( {p_{i} + {\ln 1} - \frac{e_{i}^{k}}{e_{i}^{k}}} \right){CRC}_{i}^{k}} + {\ln \quad e_{i}^{k}}} \right)} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i)^(k)

for an ith transport channel passes a CRC check; and CRC_(i)^(k)

equals to 0 if the TTI frame under hypothesis TF_(i)^(k)

fails the CRC check or a CRC result is not available.
 5. The method ofclaim 1 wherein the step of determining the transport format based onthe transport format combination metric comprises the step ofdetermining the transport format, wherein the transport format utilizedcorresponds to the transport format having a largest transport formatcombination metric.
 6. A method for blind transport format detection,the method comprising the steps of: (a) receiving an over-the air signalcomprising I data (transport) channels; (b) determining I CyclicRedundancy Check (CRC) metrics for the I data channels; (c) determininga transport format combination metric for the I data channels based onthe CRC metrics for the I data channels; (d) repeating steps b-c foreach possible transport format combination; and (e) determining atransport format combination corresponding to a largest transport formatcombination metric.
 7. The method of claim 6 wherein the step ofreceiving the over-the-air signal all comprising I data (transport)channels comprises the step of receiving the over-the-air signalcomprising I transport channels, wherein each of the I transportchannels comprises a plurality of transport formats.
 8. The method ofclaim 6 wherein the step of determining the transport format combinationmetric based on the CRC metrics comprises the step of determining${\hat{k} = {\underset{k \in {\{{1,2,\quad \ldots \quad,K}\}}}{argmax}\left\{ {{\sum\limits_{i = 1}^{I}p_{i}} + {CRC}_{i}^{k}} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i) ^(k) for an ithtransport channel passes a CRC check; and CRC_(i)^(k)

equals to 0 if the TTI frame under hypothesis TF_(i)^(k)

fails the CRC check or a CRC result is not available.
 9. The method ofclaim 6 wherein the step of determining the transport format combinationmetric based on the CRC metrics comprises the step of determining${\hat{k} = {\underset{k \in {\{{1,2,\quad \ldots \quad,K}\}}}{argmax}\left\{ {\sum\limits_{i = 1}^{I}\left( {{\left( {p_{i} + {\ln 1} - \frac{e_{i}^{k}}{e_{i}^{k}}} \right){CRC}_{i}^{k}} + {\ln \quad e_{i}^{k}}} \right)} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i)^(k)

for an ith transport channel passes a CRC check; and CRC_(i)^(k)

equals to 0 if the TTI frame under hypothesis TF_(i)^(k)

fails the CRC check or a CRC result is not available.
 10. An apparatuscomprising: a de-multiplexer having a data stream as an input, whereinthe data stream comprises a plurality of transport channels, each havinga plurality of transport channel formats, the de-multiplexer outputtinga plurality of channels based on a particular transport formatcombination; a plurality of Cyclic Redundancy Checking (CRC) circuitry,each having one of the plurality of channels as an input and outputtinga CRC for the channel; and a logic unit having a plurality of CRC valuesas an input and outputting a transport format combination metric basedon the plurality of CRC values.
 11. The apparatus of claim 10 furthercomprising storage outputting data based on a transport formatcombination corresponding to a largest transport format combinationmetric.
 12. The apparatus of claim 10 wherein the transport formatcombination metric is based on${\hat{k} = {\underset{k \in {\{{1,2,\quad {\ldots \quad K}}\}}}{argmax}\left\{ {\sum\limits_{i = 1}^{I}{p_{i}{CRC}_{i}^{k}}} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i)^(k)

for an ith transport channel passes a CRC check; and CRC_(i)^(k)

equals to 0 if the TTI frame under hypothesis TF_(i)^(  k)

fails the CRC check or a CRC result is not available.
 13. The apparatusof claim 10 wherein the transport format combination metric is based on${\hat{k} = {\underset{k \in {\{{1,2,\quad {\ldots \quad K}}\}}}{argmax}\left\{ {\sum\limits_{i = 1}^{I}\left( {{\left( {p_{i} + {\ln 1} - \frac{e_{i}^{k}}{e_{i}^{k}}} \right){CRC}_{i}^{k}} + {\ln \quad e_{i}^{k}}} \right)} \right\}}},$

wherein p₁ε{24,16,12,8,0} and CRC_(i)^(k)

equals to 1 if a TTI frame under hypothesis TF_(i)^(k)

for an ith transport channel passes a CRC check; and CRC_(i)^(k)

equals to 0 if the TTI frame under hypothesis TF_(i)^(  k)

fails the CRC check or a CRC result is not available.